1. Field of the Invention
The present invention relates to a guide for a saw blade, and more particularly, to a self steering guide for a band saw blade, or the like.
2. Prior Art
Band saws are used in many and diverse applications, such as for cutting meat, metal plates and lumber, and in many of these applications the band saw has shown a common undesirable feature in that it has a tendency to deviate from the desired cutting path with the deviation increasing as the blade continues to depart from its intended path through the material being cut, which is normally fed through the blade in a direction parallel to the plane of the blade. One reason for this phenomenon appears to be that the blades are not produced with sufficient accuracy to result in equal cutting forces being produced by the teeth on both sides of the blades and thus the cutting edge tends to track to one side or the other of the desired cutting path. As the blade progresses through the material in this abnormal posture the material applies a force to the flat side of the blade which is presenting itself to the oncoming material which tends to increase the sideways deflection of the blade so that the blade deviation from its intended track is continuously increased. Furthermore, experience has shown that blade deviation is more pronounced at higher rates of feeding of the material past the blade.
This phenomenon results in inaccurate cuts and a reduction in useable feeding rates, as well as blade guide wear, due to the frictional forces between the blade and the blade guide. In their simplest form, blade guides take the form of a slot formed in the table upon which the material rests when it is being fed through the blade, with the sides of the slot being closely adjacent the sides of the blade so that as the blade deflects it will be biased against the blade guide and rests against the guide on one side or the other during cutting of the material. It can readily be seen that this simple blade guide configuration merely attempts to restrain blade deviation and lacks any means to impart positive corrective force thereto.
In order to overcome the shortcomings of such simple blade guides as described above, many blade guides and blade controlling mechanisms have been devised for detecting and correcting deviation of the blade off its intended course. Some of these devices utilize the physical deflection of the blade itself to apply force through a series of lever arm mechanisms to the back edge of the blade to redirect the blade back to its intended path through the material. One such device is disclosed, for example, in U.S. Pat. No. 3,116,768.
Other types of blade guide devices utilize a separate force-applying mechanism in conjunction with a blade deflection sensing system so that when deflection of the blade from its normal intended path occurs the blade guide will apply a counteracting force from an external source to again correct the position of the blade back to the intended path. This type of device is disclosed, for example, in U.S. Pat. Nos. 2.914,100 and 2,914,102.
Both of these latter types of mechanisms are fairly complicated and expensive which makes their employment in many industries unacceptable. In addition, some industries do not require the degree of control that some of these mechanisms are designed to provide and by reason of which they have become relatively complicated. There is therefore a need in such industries for a blade guide which is less complicated and thus less expensive, but which provides the degree of control necessary to maintain a reasonable alignment of the blade with the intended course of the blade through the material being cut.